“Listing on the National Register recognized the importance of these properties to the history of our country and provides them with a measure of protection,” Ruth Pierpont, the state’s deputy commissioner for historic preservation, wrote in a letter to the state senator.

The historic farmstead at the corner of Main Road and Tuthills Lane was officially listed on the National Registry on Aug. 5, after having been placed on the New York State Register of Historic Places in June.

The 2.5-acre property is owned by Dayna Corlito of Hampton Bays, who applied for the federal designation, and it is currently home to Century 21 Albertson Real Estate.

“I’m very excited about it,” Ms. Corlito said Monday. “Once we found out about New York State, I was really hoping it would get on the National Register too.”

Ms. Corlito said the Riverhead Town Planning Department has twice denied her application to put a retail wine shop and tasting room in the large barn toward the rear of the property, and as a result, she will need to go to the Zoning Board of Appeals for setback variances and for a use variance, the latter of which is more difficult to obtain.

She said the real estate office also will remain in the main building, where it has been since 1997.

Inclusion on the National Register means that owners of income producing properties may quality for federal and/or state income tax benefits, and homeowners in qualifying census tracts may qualify for state income tax benefits for approved work.

“We’re certainly delighted,” said Richard Wines, the chairman of Riverhead Town’s Landmarks Preservation Commission. “We obviously hope to have all of Main Road on the National Registry some day so all of the older houses can benefit from the generous federal and state tax credits that are available with this designation, but it’s nice to have one property showing the way.”

The main building on the Tuthill farm property, a Greek Revital style structure, was built around 1840 as a residence for Daniel Tuthill and his family, and a large English-style barn was built behind it in 1884 by Daniel’s son, Henry.

This building housed what was known as a potato cellar, Mr. Wines said.

Another potato barn was built on the east side of the house in the 1930s and is one of the first semi-underground potato barns in the state, Mr. Wines said.

The main building contained what was known as a “milk shed,” a small heavily insulated shed designed to keep milk and dairy fresh, according to Mr. Wines.

There are now 10 sites individually listed on the National Register of Historic Places plus the Main Street National Register District, which stretches roughly from Griffing Avenue to Maple Avenue, and has 37 “historic resources,” according to Mr. Wines.

He is hoping to get area along Second and Third Street between Griffing Avenue and Ostrander Avenue included as well.